Abstract

Episodes of transient loss of consciousness (TLOC) events pose diagnostic difficulties, as the causes are diverse, carry vastly different risks, and span various specialties. An inconsistent terminology contributes to the confusion. Here, we present a classification scheme for TLOC, based on ongoing multidisciplinary efforts including those of the Task Force on Syncope of the European Society of Cardiology. We also discuss the pathophysiology of TLOC and the key clinical features that aid diagnosis. TLOC is defined as an apparent loss of consciousness with an abrupt onset, a short duration, and a spontaneous and complete recovery. Syncope is defined as TLOC due to cerebral hypoperfusion, and is divided into reflex syncope (synonymous with neurally mediated syncope), syncope due to orthostatic hypotension, and cardiac syncope (arrhythmic or associated with structural cardiac disease). The other major groups of TLOC are generalized epileptic seizures, functional TLOC (psychogenic TLOC mimicking either epilepsy or syncope), and a further group of miscellaneous disorders. The management of patients who experience TLOC requires the recognition of the defining features of each of the major groups, and cooperation between different clinical specialties.

Author affiliations

1. Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands.
2. Epilepsy Institute of the Netherlands (SEIN), Heemstede, The Netherlands.
3. University of Minnesota Medical School, Cardiac Arrhythmia Center, Minneapolis, MN, USA.
4. Department of Internal Medicine, Academic Medical Centre, Amsterdam, The Netherlands.

Correspondence to: Department of Neurology, Section of Clinical Neurophysiology, Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands
Email: j.g.van_dijk@lumc.nl

Published online 14 July 2009